Deadly jellyfish heading our way

CLIMATE change has dramatically altered the ocean current flowing down Australia's east coast, sending water temperatures soaring, rearranging the distribution of sea life and making the water more acidic.

By 2070, CSIRO marine biologists warned yesterday, NSW could have dugongs frolicking off the coast - and box jellyfish wreaking havoc on tourism.

In their report, Impacts of Climate Change on Australian Marine Life, Alistair Hobday and his co-authors found that climate change posed a multibillion-dollar threat to "the economic and ecological sustainability of fisheries, aquaculture and tourism". The scientists found that since the CSIRO began taking measurements off eastern Tasmania 60 years ago, the average winter temperature had jumped 1.5 degrees and summer temperatures 2 degrees.

Tasmania's water temperature had risen at twice the rate of its atmospheric temperature in the past century - about 0.8 degrees.

The explanation was that climate change had increased the strength of the key current channelling warm water down from Queensland. "It is a clearly demonstrated change in the current," Dr Hobday said. The cause of the change could be the rise in greenhouse gases from human activity, the impact of the hole in the ozone layer, or both.

Significant variations in east-coast marine biology had been observed, Dr Hobday said. "Tropical species are being pushed further south," he said, with 34 species of fish not previously seen in Tasmania having been recorded in the past 10 years.

A species of sea urchin from NSW had appeared in the past 20 years. "It's a voracious kelp eater," Dr Hobday said. "When you lose the kelp, you lose abalone and rock lobsters." There was also evidence that krill, eaten by sea birds, was in decline.

The report says higher levels of carbon dioxide in the sea will lead to a 30 per cent increase in water acidity, threatening to dissolve shell creatures and coral.